Recent content by trina1990

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    Horizon distance and observers altitude problem

    Yes, i tried with this. . Thanks a lot for helping
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    Visibility of sun in different altitudes

    I've to show , " at the spring equinox for a place of latitude ø, the sun will become visible at the top of a tower of height " H " feet, about " 13.94(root over )H * sec ø " But as far i made calculations, i got the amount of "4.24 root over H * sec ø " I used all the measurements in...
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    Horizon distance and observers altitude problem

    Here's a problem from an astronomy book "the top of the mountain 1000 m in height can just be visible seen from a ship approaching the land where the mountain is situated. . If the observer's eye is 30 m above sea level. Then how far the ship is from the mountain? " The main problem is i...
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    Circumpolar star declination problem

    oki. . Got it. . Many many thanks
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    How Do You Calculate Telescope FOV Using Earth's Rotation?

    a problem from an olympiad "A student tries to measure field of view (FOV) of the eyepiece of his/her telescope, using rotation of the Earth. To do this job, the observer points the telescope towards Vega (alpha Lyr., RA: 18.5h , Dec: +39° ), turns off its "clock drive" and measures trace...
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    Circumpolar star declination problem

    hi, heres' problem from an international olympiad "The Damavand Mountain is located at the North part of Iran, in south coast of Caspian Sea. Consider an observer standing on the Damavand mountaintop (latitude = 35° 57′ N; longitude = 52° 6' E; altitude 5.6 x 10^3m from the mean sea level)...
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    Circumpolar star declination problem

    well, so there altitude matters...i can see the stars below horizon due to my high altitude & refraction on the atmospheric layers... but can you please suggest me the clue to derive this declination?
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    Photons collected be telescope apertures

    thanks a lot... the book in which i found this problem showed answer of this problem to be 3x10^7 photons per second... that's why i got so much stunned with my result...:confused: but a similar problem with different coefficients shows a result very close to my calculation.. anyway i...
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    Circumpolar star declination problem

    thanks for answering... of course it's that, but my question is how can i explain this procedure mathematically?... i just wanted to know the process of measering star declination &then asked if the circumpolar condition changes if i change the altitude? for circumpolar stars i only know...
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    Photons collected be telescope apertures

    the energy output of a star is such at the surface of the Earth it provides 5x10^-19 WM^-2 in the visible part of the spectrum... how many photons are collected per second by a 500mm diameter telescope? i don't know if there's any definite formula to drive the answer...but i tried this way...
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    Circumpolar star declination problem

    The Damavand Mountain is located at the North part of Iran, in south coast of Caspian Sea. Consider an observer standing on the Damavand mountaintop (latitude = 35° 57′ N; longitude = 52° 6' E; altitude 5.6 x10^3m from the mean sea level) and looking at the sky over the Caspian Sea. What...
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    Deriving the Relation for Escape Velocity from a Proto-Star Cloud

    yes...it makes sense to me that escape velocity & falling velocity is the same for the system... but unfortunately i didn't get the 2nd para of your answer.. can you please provide me some more hints to derive the original formula given in the question?
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    Determining the mass of globular cluster?

    thank you ... i didn't even heard of this theory earlier as i am not a physics student... any way i got the equation for the mass to be M=2v^2R/G now i can easily solve this out... but can you please help me a bit more to completely understand the equation..? as it says the kinetic...
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    Determining the mass of globular cluster?

    : Estimate the mass of a globular cluster with the radius of R=20pc and root mean square velocity of stars equal to Vrms=3km/s i can apply the formula like Vrms=(root over) 3RT/M ( where R=gas constant, T= absolute temperature, M=mass of the cluster) but here the variable of the "T" is...
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    Deriving the Relation for Escape Velocity from a Proto-Star Cloud

    : Derive a relation for the escape velocity of an object, launched from the center of a proto-star cloud. The cloud has uniform density with the mass of M and radius R... Ignore collisions between the particles of the cloud and the launched object. If the object were allowed to fall...
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